Epitaxial Growth of ZnO by Sol-Gel Method

Epitaxial films of ZnO have been synthesized by the sol-gel method using ZnO buffer layers on sapphire (001) substrates. The buffer layers of 50-nm ZnO were epitaxially grown by metal organic chemical vapor deposition prior to the sol-gel process and significantly improved the crystallinity of the sol-gel ZnO. The six-fold symmetry observed in X-ray diffraction phi-scan spectra confirmed the epitaxial nature of the sol-gel ZnO films. Excitonic recombinations were dominant in the photoluminescence, while defect-related emissions around 3.31 to 3.32 eV, which are commonly observed in polycrystalline sol-gel films, were not observed in the sol-gel ZnO with ZnO buffer layers.